diff options
Diffstat (limited to 'arch/x86/lib/scu.c')
| -rw-r--r-- | arch/x86/lib/scu.c | 168 |
1 files changed, 168 insertions, 0 deletions
diff --git a/arch/x86/lib/scu.c b/arch/x86/lib/scu.c new file mode 100644 index 0000000000..bb23d0b829 --- /dev/null +++ b/arch/x86/lib/scu.c @@ -0,0 +1,168 @@ +/* + * Copyright (c) 2017 Intel Corporation + * + * Intel Mobile Internet Devices (MID) based on Intel Atom SoCs have few + * microcontrollers inside to do some auxiliary tasks. One of such + * microcontroller is System Controller Unit (SCU) which, in particular, + * is servicing watchdog and controlling system reset function. + * + * This driver enables IPC channel to SCU. + * + * SPDX-License-Identifier: GPL-2.0+ + */ +#include <common.h> +#include <dm.h> +#include <regmap.h> +#include <syscon.h> +#include <asm/cpu.h> +#include <asm/scu.h> +#include <linux/errno.h> +#include <linux/io.h> +#include <linux/kernel.h> + +/* SCU register map */ +struct ipc_regs { + u32 cmd; + u32 status; + u32 sptr; + u32 dptr; + u32 reserved[28]; + u32 wbuf[4]; + u32 rbuf[4]; +}; + +struct scu { + struct ipc_regs *regs; +}; + +/** + * scu_ipc_send_command() - send command to SCU + * @regs: register map of SCU + * @cmd: command + * + * Command Register (Write Only): + * A write to this register results in an interrupt to the SCU core processor + * Format: + * |rfu2(8) | size(8) | command id(4) | rfu1(3) | ioc(1) | command(8)| + */ +static void scu_ipc_send_command(struct ipc_regs *regs, u32 cmd) +{ + writel(cmd, ®s->cmd); +} + +/** + * scu_ipc_check_status() - check status of last command + * @regs: register map of SCU + * + * Status Register (Read Only): + * Driver will read this register to get the ready/busy status of the IPC + * block and error status of the IPC command that was just processed by SCU + * Format: + * |rfu3(8)|error code(8)|initiator id(8)|cmd id(4)|rfu1(2)|error(1)|busy(1)| + */ +static int scu_ipc_check_status(struct ipc_regs *regs) +{ + int loop_count = 100000; + int status; + + do { + status = readl(®s->status); + if (!(status & BIT(0))) + break; + + udelay(1); + } while (--loop_count); + if (!loop_count) + return -ETIMEDOUT; + + if (status & BIT(1)) { + printf("%s() status=0x%08x\n", __func__, status); + return -EIO; + } + + return 0; +} + +static int scu_ipc_cmd(struct ipc_regs *regs, u32 cmd, u32 sub, + u32 *in, int inlen, u32 *out, int outlen) +{ + int i, err; + + for (i = 0; i < inlen; i++) + writel(*in++, ®s->wbuf[i]); + + scu_ipc_send_command(regs, (inlen << 16) | (sub << 12) | cmd); + err = scu_ipc_check_status(regs); + + if (!err) { + for (i = 0; i < outlen; i++) + *out++ = readl(®s->rbuf[i]); + } + + return err; +} + +/** + * scu_ipc_simple_command() - send a simple command + * @cmd: command + * @sub: sub type + * + * Issue a simple command to the SCU. Do not use this interface if + * you must then access data as any data values may be overwritten + * by another SCU access by the time this function returns. + * + * This function may sleep. Locking for SCU accesses is handled for + * the caller. + */ +int scu_ipc_simple_command(u32 cmd, u32 sub) +{ + struct scu *scu; + struct udevice *dev; + int ret; + + ret = syscon_get_by_driver_data(X86_SYSCON_SCU, &dev); + if (ret) + return ret; + + scu = dev_get_priv(dev); + + scu_ipc_send_command(scu->regs, sub << 12 | cmd); + return scu_ipc_check_status(scu->regs); +} + +int scu_ipc_command(u32 cmd, u32 sub, u32 *in, int inlen, u32 *out, int outlen) +{ + struct scu *scu; + struct udevice *dev; + int ret; + + ret = syscon_get_by_driver_data(X86_SYSCON_SCU, &dev); + if (ret) + return ret; + + scu = dev_get_priv(dev); + + return scu_ipc_cmd(scu->regs, cmd, sub, in, inlen, out, outlen); +} + +static int scu_ipc_probe(struct udevice *dev) +{ + struct scu *scu = dev_get_priv(dev); + + scu->regs = syscon_get_first_range(X86_SYSCON_SCU); + + return 0; +} + +static const struct udevice_id scu_ipc_match[] = { + { .compatible = "intel,scu-ipc", .data = X86_SYSCON_SCU }, + { /* sentinel */ } +}; + +U_BOOT_DRIVER(scu_ipc) = { + .name = "scu_ipc", + .id = UCLASS_SYSCON, + .of_match = scu_ipc_match, + .probe = scu_ipc_probe, + .priv_auto_alloc_size = sizeof(struct scu), +}; |